Modeling LNAPL transport in the Vadose Zone

Conference · Sat Jul 01 04:00:00 EDT 1995

OSTI ID:102510

Tomasko, D; Butler, J P

Groundwater contamination is an ever growing problem. In particular, problems associated with light non-aqueous phase liquids (LNAPLs) such as gasoline, diesel fuel, and jet fuels are becoming more common. This paper presents the development and application of an analytical model for predicting LNAPL concentrations at the water table. Based on the volume of the spill, the model has two parts: a pancake model for predicting the behavior of the LNAPL if the spill volume is large enough to reach the water table; and an advection/dispersion model that assumes that the LNAPL does not reach the water table as a slug, but creates a contaminated soil layer from which soluble LNAPL components can be mobilized and transported vertically downward while undergoing advection, dispersion, sorption, volatilization, and biodegradation. Maximum and current concentrations are calculated at the water table for the pancake model using a solubility-limited approach, and an analytical expression derived using Laplace transforms for the advection/dispersion model. The behavior and sensitivity of the model is evaluated for a hypothetical site using an LNAPL having ten components that represent a cross section of organic compounds commonly found in spills including BTEX, branch alkanes, and polynuclear aromatic hydrocarbons. Results of the study indicate that the most important LNAPL group is the BTEX compounds, and that, of these, benzene would have the largest maximum concentration at the water table because of its relatively long biodegradation half-life. Other parameters of importance include total precipitation, depth to the water table, and the fraction of organic carbon in the soil.

• Research Organization: Argonne National Lab., IL (United States)
• Sponsoring Organization: Department of Defense, Washington, DC (United States)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 102510
• Report Number(s): ANL/EA/CP--85961; CONF-9508138--1; ON: DE95014153
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
ADVECTION
DISPERSIONS
GROUND WATER
MATHEMATICAL MODELS
NONAQUEOUS SOLVENTS
SOILS